Skin diseases and conditions, such as acne, dermatitis, and rosacea, can be further complicated by way of microbial colonization and/or infection. For example, acne, a well known and common skin disease, has very different forms as well as grades of severity, from simple acne vulgaris, extending to the more dangerous forms such as acne conglobate, which can lead to severe disfigurements of the skin. Disregarding it, as well as excessive and improper treatment, can lead to irreversible scars and changes of the skin, and consequent adverse effects to quality of life. To a large extent, the aforementioned is also true for seborrheic dermatitis and other skin diseases in their different forms such as herpes, from simple irritations of the skin up to severe and irreversible changes of epidermis.
Traditionally, there were basically two possibilities for the therapy of acne, seborrheic dermatitis and other related skin diseases: Topical (exterior) treatment and oral treatment which is effective via the metabolism. The oral treatment, for example, is principally used only for very severe forms of acne, since retinoids and related active agents may have very strong side effects. Even the topical remedies traditionally used were of questionable safety when applied at the concentration necessary for the desired therapeutic effect. Antibiotic preparations, mainly used for fighting secondary infections, are generally subject to prescription. In addition, benzoyl peroxide, which is the topical remedy most used, is by no means as harmless as it would be desirable for at least the treatment of young people. In addition to its suspected carcinogenic effect established in tests with animals, it is very aggressive, and its main effect consists of the oxidation of the upper skin layers like a chemical scalpel, thereby chemically isolating these layers and causing irritation. The same applies for salicylic acid which is used to dissolve the skin by its keratolytic effect.
Onychomycosis—nail fungal infection—affects 30-60 million patients each year in the United States. It is the most common disease of the nails and constitutes about a half of all nail abnormalities. This condition may affect toenails or fingernails, but toenail infections are particularly common. The prevalence of onychomycosis is about 6-8% of the United States adult population. Common signs of onychomycosis include a thickened, yellow, or cloudy appearance of the nails. The nails can become rough and crumbly, and can separate from the nail bed. Patients with onychomycosis may experience significant psychosocial problems due to the appearance of the nail.
The causative pathogens of onychomycosis include dermatophytes, Candida, and nondermatophytic molds. Dermatophytes are the fungi most commonly responsible for onychomycosis in the temperate western countries, while Candida and nondermatophytic molds are more frequently involved in the tropics and subtropics with a hot and humid climate. Trichophyton rubrum is a common dermatophyte involved in onychomycosis. Other dermatophytes that may be involved are T. mentagrophytes, Epidermophyton floccosum, T. violaceum, Microsporum gypseum, T. tonsurans, T. soudanense and the cattle ringworm fungus T. verrucosum. Other causative pathogens include Candida and nondermatophytic molds, in particular members of the mold generation Scytalidium (now called Neoscytalidium), Scopulariopsis, and Aspergillus. Candida spp. are known to cause fingernail onychomycosis in people whose hands are often submerged in water. Scytalidium mainly affects people in the tropics, though it persists if they later move to areas of temperate climate. Control of these pathogens can be used to treat onychomycosis.